The present invention relates generally to photovoltaic cells commonly referred to as solar cells and, more particularly, is directed to integrated photovoltaic generators containing at least two photovoltaic cells.
As is well known in the art, photovoltaic cells are semiconductor devices having electrical junctions which are capable of converting incident light into electrical energy. With silicon type photovoltaic cells, a single cell is typically capable of generating an electrical potential of up to about 0.5 volts with sufficient incident light. Since most photovoltaic cell applications require a voltage greater than 0.5 volt, it has been common practice to electrically connect a plurality of cells in series to thereby form a photovoltaic generator capable of producing the desired voltage.
A commonly used method for making such a photovoltaic generator, particularly for generators of minimum size to be used by the digital watch industry to recharge a watch battery, is to provide a plurality of cells, each having a metallized contact surface coplanar with each major surface of the cell and then join the cells in a "shingle" type assembly. In such an assembly, the metallized portion of the top surface of one cell is joined by soldering to the metallized portion of the bottom surface of another cell, the metallized top portion of the latter cell being joined to the bottom portion of yet another cell, etc., such that each cell of the generator partially overlaps adjacent cells. In this manner, the desired number of cells to provide the required voltage for the generator can be achieved in a compact and sturdy assembly of cells.
A disadvantage of such an assembly for a photovoltaic generator, among others, is that generally the cells must be joined to each other in a manual operation. Even with specially designed features and sophisticated assembly aids, the labor component of the total cost of photovoltaic generator of the type described above is unacceptably high.